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Cr 197 & Gum 15
Hi §AB, Andrew & All,
AJ wrote:
"Cr 197 (08 44.7m -41 deg 17') and Gum 15 / RCW 32 (08h 44.6m -41 deg 17') is an open cluster containing the small bright nebula known as Gum 15 which surrounds the multiple star of I 815. Surprisingly missed in AOST2"
Well, this was at the top of my list last night after this discussion and I can't find myself in agreement AJ about it being overlooked for AOST. Sorry!
I observed it with the 18" with the 16mm T2 at x139 35' TF, 20mm T2 at x111 with 44' TF and 26mm T5 x85 58' TF, with and without UHC, OIII and H-Beta filters and the best view was with the 20mm T2 unfiltered.
The cluster is a poor and scattered one with no central condensation apparent and is completely resolved. There are slightly more stars N of the central star than south of it. It is dominated nr centre by the multiple star Innes 815. All three of the faint companions in Innes 815 are easily seen at x111. The cluster contains 20-odd stars scattered over about 15 arc-mins diameter and is not detatched from its surrounding fields -- the borders of the cluster are not defined at all and the field seems equally rich as the cluster. Large variation in brightness between members between mag 7 to 13.
The visible portions of Gum 15 is considerably less than the DSS shows and are pretty faint. I thought the best view was without the filter. The nebula is classified as "E" but it does not seem to have much/any emission component as to me it seemed dimmed to the UHC and completely disappered with the O III and H-Beta. Only a maybe 2-3 arc-min diameter very LSB haze surrounding but mainly to the N of Innes 816 with no defined border.
I also took another look at the (nearby) OC NGC 2671 at x138 and in the 18" it is a nice object. Seems about 7 arc-mins in diameter as a well detatched splash of 3 dozen-odd faint stars mainly in the 13th to 14th mag range pretty homogenous in brightness. Within the cluster a large triangular-shaped group on the N side stands out with points of that triangle at centre, PA 30 and PA 330, about 3-4 arc-mins a side. Quite nice. Seems completely resolved and no residual haziness is evident. The NGC indicates a diameter of 4 arc-mins -- I think this is a bit of an under-estimate -- more like 7 arc-mins and the magnitude should be more like about 9 rather than 11.6v.
Best,
Les D
Contributing Editor
AS&T
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